(1) In matters involving an adjudicative proceeding, the commission may designate as presiding officer a member of the commission, or an administrative law judge assigned by the office of administrative hearings under the authority of chapter 34.12 RCW.

(2) A person who has served as an investigator, prosecutor, or advocate in any stage of an adjudicative proceeding, or someone who is subject to the authority or direction of such a person, may not serve as a presiding officer in the same proceeding.